20711557 has 2 divisors, whose sum is σ = 20711558. Its totient is φ = 20711556.

The previous prime is 20711543. The next prime is 20711563. The reversal of 20711557 is 75511702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17564481 + 3147076 = 4191^2 + 1774^2 .

It is a cyclic number.

It is not a de Polignac number, because 20711557 - 2¹⁹ = 20187269 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20711057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10355778 + 10355779.

It is an arithmetic number, because the mean of its divisors is an integer number (10355779).

Almost surely, 2^20711557 is an apocalyptic number.

It is an amenable number.

20711557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20711557 is an equidigital number, since it uses as much as digits as its factorization.

20711557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2450, while the sum is 28.

The square root of 20711557 is about 4550.9951658950. The cubic root of 20711557 is about 274.6234272732.

The spelling of 20711557 in words is "twenty million, seven hundred eleven thousand, five hundred fifty-seven".